It is generally well known in the art that it has proven difficult to sew a wrinkle-free seam when attaching rubber or elastic tape to the edge of a non-stretchable workpiece such as cotton or the like. The sewing operator had been faced with the perplexing problem of how to advance equal lengths of the workpiece and elastic between the presser foot and the feed mechanism without stretching the elastic. That is, the pressure on the foot which is necessary to advance the workpiece through the machine may cause the elastic to stretch thus resulting in certain amounts of wrinkling.
It may be suggested that one solution to the stretching of the elastic problem may be to reduce the pressure on the foot to a point whereat the stretching of the elastic is eliminated. However, the provision of such a slight pressure may prove to be insufficient for the foot to interreact with the feed mechanism in advancing the workpiece through the machine.
Further, when the presser foot passes over a seam or other thickened portion of the workpiece, the entirety of the foot may be lifted or tilted. As one skilled in the art may appreciate, when the presser foot bottom is removed or raised from contact with the workpiece it enhances the possibility of skipped stitches. These conditions are, of course, objectionable.